A Quantum Dot (QD) is a semiconductor nanostructure that chains conduction band electron, valence band hole and exciton in three spaces, and also known as a Nano crystalline, and a nanoparticle that forms by II-VI group element or III-V element. A particle size of the quantum dot is generally ranged within 1˜10 nm. Because electrons and holes are limited by the quantum dot, continuous band structure becomes a discrete energy level structure that has molecular characteristics and can emit florescent light after being excited. A Chip Scale Package (CSP) LED, as a frameless LED, has features of simple manufacturing process, good heat dissipation, small light-emitting surface such that the CSP LED has become an important development direction of the LED.
FIG. 1 is an absorption spectrum of red light quantum dot and green light quantum dot. FIG. 2 is an emission spectrum of red light quantum dot and green light quantum dot. In FIG. 1 and FIG. 2, a gray line represents the green light quantum dot, the black line represents the red light quantum dot. From FIG. 2, the FWHM (full width at half maximum) of the red light quantum dot and the green light quantum dot is very narrow such that adding quantum dots in a light source can greatly increase the color gamut of the liquid crystal display device.
However, the temperature quenching of the quantum is very serious, when the temperature is increased, the luminous efficiency is decreased. Besides, if the quantum dots are exposed in a water and oxygen environment, the luminous efficiency will decrease quickly. Accordingly, the quantum dot requires isolating the water and oxygen, the high temperature or providing a better heat dissipation environment.